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Re: Newbie coding question - format error

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  Re: Newbie coding question - format error Sibylle Koczian <nulla.epistola@web.de> - 2014-06-29 16:09 +0200
    Re: Newbie coding question - format error Roy Smith <roy@panix.com> - 2014-06-29 10:47 -0400

#73731 — Re: Newbie coding question - format error

Am 29.06.2014 09:06, schrieb Martin S:
>
> x=int(input('Enter an integer '))
> y=int(input('Enter another integer '))
> z=int(input('Enter a third integer '))
> formatStr='Integer {0}, {1}, {2}, and the sum is {3}.'
> equations=formatStr.format(x,y,z,x+y+z)
> print(equations)
> formatStr2='{0} divided by {1} is {2} with a reminder of {3}'
> equations2=formatStr2.format(x,y,x//y,x%y)
> print(equations2)
>
> And obviously this works.
> But the question is: if I want to keep the results of {2} and {3}
> between the first instance (formatStr) and the second (formatStr2)  how
> would I go about it? Apprently using {4} and {5}  instead results in a
> index sequence error as in
>
> IndexError: tuple index out of range
>

{0} ... {3} are just placeholders in your format strings, they can't 
exist outside of them. And you can't put more placeholders into the 
format string than you've got values to put into them. That's what the 
IndexError is about.

But nothing forces you to put your calculations into the call to 
format(). Instead, give names to the results you want to keep:

mysum = x + y + z
equation_sentence_1 = formatStr.format(x, y, z, mysum)
...
myquotient = x // y
myremainder = x % y
# or, nicer: (myquotient, myremainder) = divmod(x, y)
equation_sentence_2 = formatStr2.format(x, y, myquotient, myremainder)
...

Now you still can do all you want with mysum, myquotient, myremainder.

HTH
Sibylle

BTW: it's better to post here using text, not HTML. Not all newsreaders 
and mail clients used for this list cope well with HTML. And it's just 
luck that your code doesn't contain indentations, they might not 
survive. Moreover code is much more readable with a fixed font which you 
get as a by-product using text.

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#73732

In article <mailman.11326.1404051003.18130.python-list@python.org>,
 Sibylle Koczian <nulla.epistola@web.de> wrote:

> Am 29.06.2014 09:06, schrieb Martin S:

> > IndexError: tuple index out of range
> >
> 
> {0} ... {3} are just placeholders in your format strings, they can't 
> exist outside of them. And you can't put more placeholders into the 
> format string than you've got values to put into them. That's what the 
> IndexError is about.

This seems like a confusing error message to me.  I've opened 
http://bugs.python.org/issue21879 on this.

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